package com.cw.lang.common.framework.sentinel.exception.handle;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.stereotype.Component;

import com.alibaba.csp.sentinel.adapter.spring.webmvc.callback.BlockExceptionHandler;
import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.alibaba.csp.sentinel.slots.block.degrade.DegradeException;
import com.alibaba.csp.sentinel.slots.block.flow.FlowException;
import com.alibaba.csp.sentinel.slots.system.SystemBlockException;
import com.alibaba.fastjson.JSON;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

/**
 * 异常处理页面
 */
@Component
public class ExceptionHandlerPage implements BlockExceptionHandler {
    //BlockException 异常接口,包含Sentinel的五个异常
    @SentinelResource
    //用于定义资源，并提供可选的异常处理和 fallback 配置项。其主要参数如下:
    // FlowException 限流异常
    // DegradeException 降级异常
    // ParamFlowException 参数限流异常
    // AuthorityException 授权异常
    // SystemBlockException 系统负载异常
    @Override
    public void handle(HttpServletRequest request, HttpServletResponse response, BlockException e)
    throws Exception {
        response.setContentType("application/json;charset=utf-8");
        ResponseData data = null;
        if (e instanceof FlowException) {
            data = new ResponseData(-1, "接口被限流了...");
        } else if (e instanceof DegradeException) {
            data = new ResponseData(-2, "接口被降级了...");
        } else if(e instanceof SystemBlockException){
            data = new ResponseData(-1, "系统被限流了...");
        }
        response.getWriter()
            .write(JSON.toJSONString(data));
        //@SentinelResource的使用
        //在定义了资源点之后，我们可以通过Dashboard来设置限流和降级策略来对资源点进行保护。同时还能
        //通过@SentinelResource来指定出现异常时的处理策略。
        //@SentinelResource 用于定义资源，并提供可选的异常处理和 fallback 配置项。其主要参数如下:
    }
}
@Data
@AllArgsConstructor//全参构造
@NoArgsConstructor//无参构造
class ResponseData {
    private int code;
    private String message;
}